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I understand everything except for the fact HOW they get the P-Value = .00077666

ID: 3322788 • Letter: I

Question

I understand everything except for the fact HOW they get the P-Value = .00077666. Can anyone tell me how they figured this out with a TI84 calculator?

Thank you!

15. Sleep Do more than 50% of US adults feel theyget enough sleep? According to Gallup's December 2004 Lifestyle poll, 55% of U.S. adults said that that they get enough sleep. The poll was based on a random sample of 1003 U.S. adults. Test an appropriate hypothesis and state your conclusion in the context of the problem. ore) 1003 must be less "thon 10% of oll US odults, also need /O or mee- s.ccesse and £a :lores. Sreeuce s 7.50 A P.So bosed on low p-velvc 4 oo3 T hereis evidence fhab SSSU 2- sleep;s more then So%,

Explanation / Answer

Oh! Its easy. He' just converting a 1 tailed Z value into p-value.

So, the p-value is essentially P(Z>3.1646) ( note that the hypothesis is 1 directional , and hence we use 1 sided as p-value)

You can use software or Excel to solve this. I could have used the table, but table will not give you the p-value for exact 3.1646:

On Excel: =1-NORMSDIST(3.1646) = .00077666

Or use this tool at this website to arrive at the same answer:

http://www.socscistatistics.com/pvalues/normaldistribution.aspx

On the TI84 do the following:

Right Tailed z-test:

1) Calculate z_calc (z_test)

2)2nd DISTR

3) Scroll down to normalcdf

4) ENTER

5) Now enter: z_calc, 1000, 0,1)

6) ENTER

7) Output is the P-value